# Electromagnetic shower

1. Jan 29, 2008

### stunner5000pt

1. The problem statement, all variables and given/known data
A 1 TeV cosmic electron strikes the surface of the ocean. Describe what
happens to the electron. What is the maximum number of electrons in the resulting
shower? At which depth does the maximum occur?

2. The attempt at a solution

My textbook gives the max number of particles to be
$$N_{max} = E_{0}/E_{C}$$
where $$E_{C} = 600MeV/Z$$
and E0 is the energy of the incident electron

Since the electron is striking water molcules should i use Z= 18? or 16? The reason for this debate is because the oxygen is so much larger than the oxygen atom is so much larger than the hydrogen atom. As a reuslt the cross section favouirs the oxygen atom. But i suspect that the quesiton is asking for a treatment of the water molecules like large atoms?

Thanks for your help and input!